The explosive progress in cardiovascular surgery over the last decade has necessitated the development of materials and surfaces that are more and more thromboresistant. However, the search for such materials has remained largely trial-and-error with little consideration of the mechanism involved in thrombus formation on foreign surfaces. Our study has been directed toward elucidating these mechanisms. The first observable event occurring when blood contacts a foreign surface is adsorption of plasma proteins onto the surface and we have found that this adsorption determines the subsequent adherence of platelets. It was hypothesized that platelet adhesion to surfaces occurs through the formation of complex bridges between platelets and adsorbed glycoproteins. We have studied protein adsorption and interactions of oligosaccharide groups in fibrinogen and gammaglobulins with platelets. The results provided indirect evidence for the involvement of platelet-protein reactions in platelet adhesion to surfaces. BIBLIOGRAPHIC REFERENCES: "cAMP and Platelet Adhesion to Silastic Surfaces." R. G. Lee and S. W. Kim. Thrombosis Research 8 III (1976).